Charging coke oven blended coal and an overlay of briquettes

ABSTRACT

This specification discloses a carbonization method of coal briquette which made from non-coking coal and poor coking coal. According to this method, a formed coke for blast furnace can be produced economically by using conventional coke oven.

United States Patent Nire May 13, 1975 [54] CHARGING COKE OVEN BLENDEDCOAL 1,030,333 6/1912 Rusby et a1. 201/40 X AND AN OVERLAY OF BRIQUETTES1,918,162 7/1933 Willson 201/40 X 3,15l 04l 9/1964 Heinze et a1 201/6[75] Inventor: Naomichi Nire, Takatsukl, ap 3,441,480 4/1969 Ban 201/40x [73] Assignee: Sumitomo Metal Industries Limited,

osaka Clty Japan Primary Examiner-Norman Yudkoff 1 Filed! Julie 1972Assistant Examiner-David Edwards [21] A pl NO x 262 672 Attorney, Agent,or Firm-Watson, Cole, Grindle &

p Watson [30] Foreign Application Priority Data June 17, 1971 Japan46-43510 [57] ABSTRACT [52] US. Cl. 201/6; 201/8; 201/24;

201/40 This specification discloses a carbonization method of [51] Int.Cl. C01b 47/10; ClOb 57/04 coal briquette which made from non-cokingcoal and [58] Field of Search 201/24, 23, 21, 40, 6, poor coking coal.According to this method, a formed 201/22, 25, 20, 8.42 coke for blastfurnace can be produced economically by using conventional coke oven.[56] References Cited 926,702 6/1909 Korting 201/40 X 1 CHARGING COKEOVEN BLENDED COAL AND AN OVERLAY OF BRIQUETTES This invention relates toa carbonization method of coal briquette consisting of poor coking coaland noncoking coal, by using a conventional coking oven.

According to the growth of the iron and steel industry all over theworld, the metallurgical coking coal is getting increasingly difficultto obtain, and this trend is becoming increasingly severe. To cope withthis trend, the blend of non-coking coal to the coal blend formetallurgical coke and the production of metallurgical coke usingnon-coking coal as the main raw material instead of the coking coal havebeen investigated.

As one manner to make the metallurgical coke from non-coking coal, thereis formed coke method. In this method, the non-coking coal is formedinto briquette prior to high temperature carbonization. However, thehigh temperature carbonization of the coal briquette in this methodcannot be done with the conventional coke oven, and a exclusiveequipment for the carbonization of the coal briquette is required. Inaddition to that, the exclusive equipment which is presently available,economically inferior to the conventional coking oven.

In another method, the coal briquette consisting of poor coking coal andsoft coking coal is used as part of coking coal charging to theconventional cokeoven (as disclosed in Japanese patent publication No.16484/1960). In this method, the caking material content in the coalbriquette is set high (with the caking material index of 66 to 90percent) to result in fusing of the coal briquette with the surroundingcoking coal, so that no trace of briquette can be found in the productcoke at all. In an example disclosed in the Japanese patent publicationNo. 16484/1960, 40 percent coal briquette are charged together with theusual coking coal into a A-ton experimental coking oven. However, thebulk density of the charging coal included the coal briquette (with 40percent) is increased to 0.78 ton per cubic meter compared to 0.72 to0.74 ton per cubic meter in case of the 100 percent usual coking coal.Therefore, in the operation of the practical coke oven, the discharge ofthe product from the coke oven get 20 percent or more of the totalcharge into the conventional coke oven. Also, it is essentiallydifferent from the above method (disclosed in the Japanese Pat.publication No. l6484/l 960) in that a formed coke can produce with theconventional coke oven.

An object of the invention is to provide a carbonization method, inwhich high temperature carbonization of coal briquette and usual cokingcoal can be done separately in the same conventional coke oven withoutrequiring any exclusive coking equipment and without causing fusion ofthe briquette one with another or the briquette with the usual cokingcoal.

According to the invention, the usual coking coal and the coal briquettecharged into the coke oven may be carbonized at the same time.

More particularly, in the carbonization method of the coal briquetteaccording to the invention, the usual coking coal, which consist of 20to 60 percent of hard coking coal, 0 to percent of soft coking coal and0 to percent of semi-hard coal so that its coke strength index (l5 mmindex in accordance with JIS, K-2l5l- 1962) is 91 or greater, is chargedin a range between 70 and 94 percent of the effective height of theconventional coke oven, and then the coal briquette coal which mainly isconsisted of the poor coking coal and the non-coking coal or non-cakingcarbonacious substance such as petroleum coke is charged in a rangebetween 6 to 30 percent of the effective oven height for hightemperature coking to obtain the metallurgical coke.

According to the invention, it is also possible to charge the usualcoking coal from the charging hole of the pusher side on the coke ovenand then charge only the briquette coal from another changing hole (onthe coke guide side).

The following example is made prior to tests using actual coke oven.

EXAMPLE This example used a standard experimental coke oven with acharging capacity of 25 kg. The quality of coals used in this exampleare as shown in Table l and Table 2 below:

Table 1 Name of coal Proportion Quality of blended coal Keystone (hardcoking coal) l5 Total moisture: 7.7 Inhercent moisture: 2.0 70 Freeswelling index: 6% Ash: 7.2 70 Balmer (hard coking coal) 2O Volatilematter: 28.8 Fixed carbon: 62.0 '7: Devis Blend (semihard l5 cokingcoal) Wollondilly (scmihard 20 Total sulfur: 0 5! coking coal) Akabira(soft coking 30 7c Size distribution coal) (3 mm): 73.3 7:-

into trouble. Table 2 In practice, therefore, in the disclosed method,the proportion of the coal briquette in the charging coal for Name ofcoal Proportion Quality of blended coal 2 t the Convennonal coke Ov.en 5to 30 he Poor caking coal 6O Inherent moisture: 1.9 most, and the poorcoking and the non-coking coal Ash: 71 cannot use r tha ab t 20 r tPetroleum coke 30 Volatile matter: 28.9 7: (non-caking) Fixed carbon:62.10% In the method according to the invention, it ls possi- Coal tarpitch 1O Total sulfur: 0.62%

ble to use the poor coking and the non-coking coal by Free swellingindex:

The blended coal shown in Table 1 is usual for producing blast furnacecoke. The blend for the coal briquette coal shown in Table 2 consists ofthe poor coking coal (with 3.2 percent inherent moisture. l 1.8 percentash, 32.3 percent volatile matter, 52.7 percent fixed carbon and freeswelling index of l and the petroleum coke having no caking property.The coke produced from this poor coking coal is inadequate as blastfurnace coke since the coke strength index is very low, being 30.9; (themm index according to .115 is 30.9 and the stability factor accordingto-ASTM D 294-64 is 7.5).

The raw materials for coal briquette mixed according to the proportionof Table 2 was pulverized less than 3 mm., and fed on to a kneader. Thecoal tar pitch in the mixture is method by the heat of hot steam blowninto the kneader and the mixture is kneaded sufficiently, and then themixture was supplied to the briquetting machine, which is a double rolltype and has a briquette pressure of about 950 kg/cm (line pressure).

The coal briquette produced in the aforementioned way has dimensions of28 mm X 19 mm and a weight of 10.1 grs. For the carbonization by theexperimental coke oven, 184 kg of the blended coal shown in Table l wasfirst charged uniformly within the carbonization chamber of theexperimental coke oven and then 45 kg of the coal briquette producedunder the above conditions charged on the blended coal. Then, the chargewas carbonized with a flue temperature of 1,160C and a coking time of 15hours and 46 minutes. After carbonization, the hot coke was dischargedout of the oven by a pusher and quenched with water.

In the above manner, it was not recognized that the formed coke fusedwith the coke made from the usual blended coal. Table 3 below showsvarious properties of these cokes. Both cokes can be used as blastfurnace coke.

Table 3 Composition and properties of cokes Formed coke The ASTMstability and hardness factors were measured according to ASTM D294-1964.

In the coke oven usually used in the iron making industry, the cokingcoal is charged into the oven from a charging hole at the top of thecarbonization chamber, and after the carbonization it is mechanicallypushed out of the oven in the horizontal direction. Also, the cokingcoal charged into the coke oven should have good caking property andshould be carbonized in the form of masses.

If coal briquette chiefly consisting of poor coking coal and non-cakingmaterial like that shown in FIG. 2, is solely charged into the cokingoven, at the time of pushing the coke out of the oven the forwardcomponent of force exerted t0 the coke (formed coke) from the pusher isreduced, so that the pushing eventually becomes impossible.

FIG. 4 lists of a galvanometer of pusher in pushing tests carried out byusing a industrial coke oven with an oven height of 4 m, which theefective dimension of carbonization chamber is 3.67 m in height, 13.68 min length and 0.70 m in width, and effective inner volume of 19.2 m(charging capacity of 13.4 tons per oven). The usual blended coal andthe coal briquette according to the invention charged into the ovenchamber, and then the charged material carbonized at a flue temperatureof 1,245C for a coking time of 14 hours and 06 minutes.

Table 4 Electric current at pusher Kind of charged coal to 72 amperes Asis apparent from Table 4, the electric current at the pushe is lowest incase of the sole usual blended coal. The electric current is slightlyincreased in case of percent, that is, 12 tons of the usual blended coaland 10 percent, that is, 1.4 tons of the coal briquette. In this case,however, the pushing operation itself was found to be the same as in theabove case. In case of 30 percent, that is, 4 tons of the coal briquettethe electric current at the pusher is further increased. In this case,due to increased resistance of the coke within the oven the pusherstopped several times during the pushing operation, but the dischargingof the coke was possible.

However, in tests conducted by charging 30 percent or more of the coalbriquette the number of stoppage of the pusher was increased, and thedischarging of the coke was difficult. Accordingly, according to theinvention the proportion of the coal briquette to be charged isrestricted to be 30 percent or less. According to the invention, thelower limit of the proportion of the coal briquette to be charged ismade to be 6 percent, because with less than 6 percent of the proportionof the poor coking coal wide reduction of the coke cost cannot beexpected.

As has been described in the foregoing, according to the invention theusual coking coal is charged in a range between 70 and 94 percent of theeffective height of the coke oven while the coal briquette is charged ina range between 6 and 30 percent of the effective oven height on theusual coking coal for separately carbonizing the usual coking coal andcoal briquette in the same coke oven by the usual high temperaturecarbonization method. Thus, it is possible to economically andinexpensively produce formed coke for blast furnace from poor cokingcoal with the conventional coke oven, and save the hard coking coal.

The coal briquette on the usual coking coal either slightly fuses ordoes not fuses at all depending upon the bituminous substance content(with less bituminous substance content the fusion being weaker).Therefore, when the oven lid is removed at the time of pushing out thecoke it is possible that coal briquette in contact ization thereof;

thereafter placing, on top of said blended coal, at sufficient amount ofcoal briquettes to fill the remainder of the effective height of theoven, said briquettes comprising an admixture of a soft coking coal anda non-coking carbonaceous substance; and

subjecting the contents of the oven to carbonization to therebysimultaneously produce blast furnace coke and coke briquettes.

1. A METHOD FOR CARBONIZING COAL BRIQUETTES UTILIZING A CONVENTIONALCOKING OVEN COMPRISING: CHARGING SAID OVEN WITH A SUFFICIENT AMOUNT OF ABLENDED COAL TO FILL THE OVEN TO A LEVEL WITHIN THE RANGE OF BETWEEN 70AND 94 PERCENT OF THE EFFECTIVE HEIGHT OF THE OVEN, SAID BLENDED COALBEING CAPABLE OF CONVERSION INTO BLAST FURNACE COKE UPON CARBONIZATIONTHEREOF, THEREAFTER PLACING ON TOP OF SAID BLENDED COAL, A SUFFICIENTAMOUNT OF COAL BRIQUETTES TO FILL THE REMAINDER OF THE EFFECTIVE HEIGHTOF THE OVEN, SAID BRIQUETES COMPRISING AN ADMIXTURE OF A SOFT COKINGCOAL AND A NON-COKING CARBONACEOUS SUBSTANCE, AND SUBJECTING THECONTENTS OF THE OVEN TO CARBONIZATION TO THEREBY SIMULTANEOUSLY PRODUCEBLAST FURNACE COKE AND COKE BRIQUETTES.